Last modified February 8, 1997

Client:Corvita Canada

Supervisor: Dr. J. Michael Lee

Students: Rajesh Khanna, Todd Deaville, William McPhee

BACKGROUND

Bioprosthetic heart valve prostheses and vascular grafts incorporate animal
or human tissues which are chemically/physically processed to reduce
immunological recognition, sterilize the tissue, and increase biostability.
Unfortunately, these processes also alter the physical properties of the
materials. A particular problem is increased bending stiffness associated
with lost mechanisms for shear deformation -- a problem which can result in
early fatigue failures and calcification. An industrial need exists for a
workable device which can rapidly measure changes in bending stiffness in
materials which are inherently *very* pliable: i.e. of low stiffness. The
immediate application is to a novel coronary artery bypass graft for humans
under development by Corvita Canada. Work will be undertaken in Dr. Lee's
Tissue Mechanics Laboratory at Dalhousie.

BENDING TESTS

Two tests to determine the bending rigidity of pliable tissue are being developed.
One testing apparatus will measure the stiffness of a "hoop" or ring of material
cut from an artery bypass graft. The second test measures the bending stiffness of
a longitudinal "strip" cut from artery bypass graft material.